Context: Adverse cardiac events have been reported in patients waiting for either coronary surgery or angioplasty. However, data on the risk of adverse events while awaiting coronary angiography are limited, and none are available from a US population.
Objective: To quantify cardiac outcomes in patients waiting for elective coronary angiography.
Design, setting, and participants: Observational cohort study of 381 adult outpatients (mean [SD] age, 55  years; 64% male; 61% white) on a waiting list for coronary angiography at a US tertiary care public teaching hospital during 1993-1994.
Main outcome measures: Rates of cardiac death, nonfatal myocardial infarction, and hospitalizations for unstable angina or heart failure as a function of amount of time spent on a waiting list.
Results: Sixty-six patients were dropped from the waiting list but were included in the study analysis. During a mean (SD) follow-up of 8.4 (6.5) months, cardiac death, myocardial infarction, and hospitalization occurred in 6 (1.6%), 4 (1.0%), and 26 (6.8%) patients, respectively. The probability of events was minimal in the first 2 weeks and increased steadily between 3 and 13 weeks. By Cox multivariate analysis, 2 variables independently identified an increased risk of adverse events: a strongly positive treadmill exercise electrocardiogram or positive stress imaging result at referral (odds ratio [OR], 2.32; 95% confidence interval [CI], 1.22-4.16; P=.01) and the use of 2 to 3 anti-ischemic medications (OR, 1.98; 95% CI, 1.19-3.96; P=.04). Among 311 patients who ultimately underwent angiography, those with adverse events had a higher prevalence of coronary disease (96% vs 60%; P<.001), more frequently required revascularization (93% vs 53%; P<.001), and had longer hospital stays (mean [SD], 6.2 [4.3] vs 1.3 [0.7] days; P=.001).
Conclusion: Our data suggest that in a cohort referred for coronary angiography, delaying the procedure places some patients at risk for death, myocardial infarction, unplanned hospitalization, a longer hospital stay, and, potentially, a poorer prognosis. Waits longer than 2 weeks should be avoided, and patients with strongly positive stress test results and those who require 2 to 3 anti-ischemic medications should be prioritized for early intervention.